Impregnation of textile fabrics



Patented July 27, 1937 UNITED STATES PATENT OFFICE MBEGNATION OF TEXTILE FABRICS No Drawing. Application September 16, 1935. Se-

rial No. 40,786. In Great Britain September 19,

7 Claims.

This invention relates to improvements in the treatment of fabrics or other textile materials of the kind known to be susceptible to treatment for the production of crease-resisting products by the aid of resinous condensation-products, hereafter termed resins for brevity.

The objects of the invention are to provide improved processes of preparing the impregnating agents, and improved processes of eflecting the impregnation, and finalcondensation. Other objects will appear later. The scope of the invention is defined in the appended claims.

According to one feature of the present inven-' tion the textile material is impregnated with a containing a potentially acid substance.

As examples of compounds which liberate acid or increase the acidity oi the solution when heated in contact with the textile material, the following may be mentionedz-ammonlum acetate, formate, citrate, maleate, tartrate, oxalate, sulphate, chloride, phosphate (monobasic, dibasic, or

tribasic) ammonium ethyl sulphate, ammonium oleyl sulphate or sulphonate, and compounds of similar bases such as monomethylamine, dimethyla-mine, the ethanolamines, the hydrazines, the cyclohexylamines, etc.

The amino type of compounds appear to liberate acid by reaction between the salt compound and the methylol compounds of the urea-like substances and/or free formaldehyde which may be present or produced.

Other types ofcompounds may be used which liberate acid on heating by hydrolysis and/or dissociation, e. g. by hydrolysis such as aluminium acetate or tartrate, but the compound chosen must not be one which prevents penetration of the fibres of the textile material by the impregnating liquor. The amount of the potentially acid substance is variable but for ammonium salts'it is convenient to add at least 1 to 2 percent and preferably from 5 to 10 or even calculated on the amount of urea, for example.

The invention also includes broadly a process of producing crease-resisting textile materials in which final heating to insolubilize the resinous material is eilected by direct contact with steam. In using urea-formaldehyde condensation products it is preferred to prepare a solution showing a ratioof 1:1.6 of urea to formaldehyde; it is preferred, moreover, that such solution should have'a viscosity of about 5 to? centipo'ises (measured at 0., water value=1) at a density of 32 to 35 Tw. which can readily be secured by using 40% formaldehyde solution.

If the density is about 30 Tw. as when employing 30% formaldehyde solution, the viscosity should-be about 3 to 5 centlpoises. Such condensates consist mainly of monomethylol and/or dimethylol urea. In such solutions, it is found that free acid and particularly strong acid, causes precipitation of a further condensation product, whereas if the acid is replaced by the corresponding ammonium salt a relatively stabilizing effect is obtained. The potentially acid substance appears to liberate acid during the drying process and/or heating process. It is thus possible to add such quantities of the potentially acid substance as will, on heating, liberate larger quantities of acid than could be added as such-to the solution, or alternatively to use a salt of a stronger acid than could be added as such to the solution. The final heating necessary to insolubillze the resin can thus be completed in a shorter time or at a lower temperature than when using free acid in the smaller quantities which cannot be exceeded since otherwise the solution would be unstable.

The behaviour of these ammonium salts is not the same as in the production of plastic masses, since in the production of crease-resisting textiles it is necessary to meet special requirements e. g. the impregnating solution must not be too fully condensed, otherwise the molecular weight of the partial condensate will be so large that it cannot penetrate within the fibres; the potentially acid substance must not precipitate the further condensate and the amount of acid must not be sufilcient to cause undue tendering of the fabric under the conditions of time and temperature of final heating,'which to secure simplicity of working and larger output should involve short heating at the lowest practicable temperature.

0n the other hand, the condensation of the resinous material should be allowed to proceed to a certain extent before impregnation, otherwise undue loss of formaldehyde will occur during drying, which loss is undesirable technically and economically.

Finally, the, quantity of the potentially acid substance is preferably suflicient to cause insolubilization of the greater part of the resinous material under the chosen conditions of final heating.

Example 1 100 gms. urea are dissolved in 200 cos. of commercial formaldehyde solution (40%) which has been neutralized and the mixture is then acidified to pH=4.5 with tartaric acid. This solution added. This salt may conveniently be added asa solution in the water which is used for the diluting operation.

Fabrics are impregnated with these solutions,

squeezed, dried at a low temperature, preferably below 110 0., heated for 2 minutes at 120 C..- washed and finished in the usual way.

Alternatively the solutions at 60 to 90% concentration mentioned above instead of being allowed to stand in the cold may be raised to say IO--80 C. and then cooled immediately. 7

Example 2 100 gms. urea are dissolved in 200 cos. of neutralized 40% formaldehyde solution. This neutral solution is allowed to condense for from 3 to 20 hours at ordinary temperature, and is then diluted to 50% concentration and 2 to 3% am monium dihydrogen phosphate added (estimated on the concentrated liquor). Fabrics are impregnated, squeezed and dried, preferably below 110 C. -During this drying process, the ammonium salt is converted to the free acid, and it is important to check the efficiency of this conversion before proceeding to the final heating. We prefer that the acidity of the impregnated and dried material should be pI-I=4.5. The goods are then heated for 2 minutes at 120 C., or for 1 minute at 140 to 150 C. Alternatively, the ammonium dihydrogen phosphate may be replaced by two to three per cent ammonium tartrate in which case the impregnated and dried cloth is heated for two minutes at 170 C.

The heated fabric is washed in 0.5% warm soap solution for 5 minutes, well rinsed with water and dried in the usual manner.

The viscosity of the concentrated mixture above was 6.5 centipoisesv (water value=1) in one experiment after twenty hours. If the solution is allowed to stand it does not gelatinize but deposits crystals of melting point 126 C. These may be collected, and used in aqueous solution in concentration of 20-25% by weight in a similar manner to the dilute solution referred to above, the amount of catalyst being 2 to 4% on the solid content. Free acid is not advisable on grounds of stability.

The crystalline product from the neutral reaction mixture gives a dimethylol urea of high solubility which is important since wecan prepare powders suitable for use in making solutions for impregnation.

After the final heating of the goods for the production of crease-resisting and recovering effects, the material may be washed or finished according to desired known methods, either mechanical or chemical, e. g. the product may be treated with swelling agents or with substances which react with either or both the cellulose and condensation product.

Example 3 a specific instance, we may mention the following:--15 kgs. of urea are dissolved in 33 kgs. of neutralized 40% formaldehyde solution and 1.3 litres of ammonium hydroxide (0.88 density) added. The mixture is either raised to boilingand cooled rapidly or allowed to stand at room temperatures for from 3 to 6 hours. In these circumstances, the viscosity is usually found to lie between 5 and 7 centipoises, (water value=1).

The mixture is then diluted to 50 to 60% and a suitable catalyst added, he. 1.5% tartaric acid or from 2 to 3% ammonium dihydrogen phosphate 'or ammonium tartrate, calculated on the concentrated mixture. The cloth is impregnated, squeezed and thoroughly dried ata temperature preferably not exceeding 110 0., until, in the case of potentially acid substances, the necessary acidity which we prefer to be pH 4.5 has developed.

The goods are then heated for 2 minutes at 170 C. in the case .of tartrate and either 1- min. at.

Mil-150 C. or 2 mins. at120 C. in the case of phosphate. Alternatively, the heating may be accomplished by passing the material through a chamber containing steam under similar conditionsof time and temperature. After heating, the goods are washed. dried and finished according to known means.

Particularly in the case of steaming at the above-mentioned lower temperatures it was unexpectedly foundthat the durability, flexibility and handle of the goods were superior to those of similar samples where condensations are effected by means of cylinders, hot air chambers, etc. Cotton goods may also be treated in the above manner but with less advantage than in the case of rayon, both as' filament and as staple fibre. This treatment is applicable broadly e. g. when using substances such as tartaric acid instead of potentially acid substances.

Example 4 commenced to separate. Further cooling of the liquor produced a total yield of of monomethylol urea of melting point C.

In view of the great instability of this substance in acid solution, we prefer to use potentially acid catalysts whose aqueous solutions are non-acidic, e. g. triammonium phosphate (heating for 2 minutes at 110 to C. or 1 minute at to C.) or ammonium tartrate (2 minutes at C.).

28 grams of this monomethylol urea was dissolved in '75 003. of water and 1 grain of tertiary ammonium phosphate was added. The textile material' was impregnated, the excess of liquid removed and the material dried at a low temperature. It was then heated for 2 minutes at 120 C.

The time and temperature of final condensation are obviously capable of variation without sacrificing the efficiency of the invention. We. are aware that it is possible to execute many variations on the above examples without sacrificing 'of urea and formaldehyde which is unstable in the novelty of our invention, e. g. other bases than ammonia may be employed, most ammonium salts and potentially acid substances can be used with condensation products and mixtures of condensation products of urea or its isomer ammonium cyanate, thiourea, biuret, phenol, adipamide, dicyandiamide, ammonium thio-cyanate, etc. Methylol ureas are particularly suitable alone or in suitable mixture with or without urea and formaldehyde. In the case of mixtures prepared at room temperatures it is possible to add the ammonium salt before or during condensation provided that such catalyzed mixtures are neutral or alkaline.

We declare that what we claim is:

1. Process of improving the crease-resistance of textile fabrics which comprises impregnating the fabric with a solution of a reaction product of urea and formaldehyde consisting mainly of a methylol urea and containing a potentially acid ammonium salt and then heating the impregnated fabric to insolubilize the resin.

2. Process of improving the crease-resistance of textile materials which consists in impregnating the material with a solution of'partially condensed resin components which is unstable in acid solution, and which solution contains a potentially acid ammonium salt, and heating the impregnated material to insolubilize the resin and produce a crease-resisting product.

3. Process of improving the crease-resistance of textile material which consists in impregnating the material with a partially condensed solution acid solution, which solution contains a potentially acid ammonium salt, and heating the impregnated material to insolubilize the resin and produce a crease-resisting product.

4. Process of improving the crease-resistance of textile materials which consists in impregnating the material with a solution of a partial condensate of urea and formaldehyde containing an ammonium salt in quantity from 1 to 15 per cent of the amount of urea, and heating the impregnated material to insolubilize the resin and produce a crease-resisting product.

5. Process as in claim 2 in which an ammonium salt of a strong mineral acid is used.

6. The process of improving the crease-resistance of a textile fabric by insolubilizing of resin Within the fibre in which the fabric is impregnated with a partially condensed solution of urea. and formaldehyde containing a potentially acid substance and in which the insolubilizing is efiected by heating the impregnated material in contact with steam.

7. A crease-resisting textile fabric containing a synthetic resin insolubilized by heating a partially condensed resinous product in situ in presence of acid liberated from an ammonium salt of a mineral acid. 1

ALBERT EDWARD BA'IIYE. JOHN THOMPSON MARSH. JOSEPH TANKARD.

WILLIAM HARLING WATSON. FREDERICK CHARLES WOOD.

DISCLAIIMER 2,088,227.Albert Edward Bettye, John Thom son Marsh, Joseph Tankard, l Vill'ia m Hurling Watson and Frederick Char es Wood, Manchester, England. IM-

PREGNATION OF TEXTILE FABRICS.

Patent dated July 27, 1937. Disclaimer filed Nov. 25, 1946, by the assignee, Tootal Broadhurst Lee Oompagiy Limited.

Hereby enters disclaimer to claims 1, 2, 3, 4, 5, and 7 in said specification.

[Ofiicz'al Gazette December 24, 1.946.]

'of urea and formaldehyde which is unstable in the novelty of our invention, e. g. other bases than ammonia may be employed, most ammonium salts and potentially acid substances can be used with condensation products and mixtures of condensation products of urea or its isomer ammonium cyanate, thiourea, biuret, phenol, adipamide, dicyandiamide, ammonium thio-cyanate, etc. Methylol ureas are particularly suitable alone or in suitable mixture with or without urea and formaldehyde. In the case of mixtures prepared at room temperatures it is possible to add the ammonium salt before or during condensation provided that such catalyzed mixtures are neutral or alkaline.

We declare that what we claim is:

1. Process of improving the crease-resistance of textile fabrics which comprises impregnating the fabric with a solution of a reaction product of urea and formaldehyde consisting mainly of a methylol urea and containing a potentially acid ammonium salt and then heating the impregnated fabric to insolubilize the resin.

2. Process of improving the crease-resistance of textile materials which consists in impregnating the material with a solution of'partially condensed resin components which is unstable in acid solution, and which solution contains a potentially acid ammonium salt, and heating the impregnated material to insolubilize the resin and produce a crease-resisting product.

3. Process of improving the crease-resistance of textile material which consists in impregnating the material with a partially condensed solution acid solution, which solution contains a potentially acid ammonium salt, and heating the impregnated material to insolubilize the resin and produce a crease-resisting product.

4. Process of improving the crease-resistance of textile materials which consists in impregnating the material with a solution of a partial condensate of urea and formaldehyde containing an ammonium salt in quantity from 1 to 15 per cent of the amount of urea, and heating the impregnated material to insolubilize the resin and produce a crease-resisting product.

5. Process as in claim 2 in which an ammonium salt of a strong mineral acid is used.

6. The process of improving the crease-resistance of a textile fabric by insolubilizing of resin Within the fibre in which the fabric is impregnated with a partially condensed solution of urea. and formaldehyde containing a potentially acid substance and in which the insolubilizing is efiected by heating the impregnated material in contact with steam.

7. A crease-resisting textile fabric containing a synthetic resin insolubilized by heating a partially condensed resinous product in situ in presence of acid liberated from an ammonium salt of a mineral acid. 1

ALBERT EDWARD BA'IIYE. JOHN THOMPSON MARSH. JOSEPH TANKARD.

WILLIAM HARLING WATSON. FREDERICK CHARLES WOOD.

DISCLAIIMER 2,088,227.Albert Edward Bettye, John Thom son Marsh, Joseph Tankard, l Vill'ia m Hurling Watson and Frederick Char es Wood, Manchester, England. IM-

PREGNATION OF TEXTILE FABRICS.

Patent dated July 27, 1937. Disclaimer filed Nov. 25, 1946, by the assignee, Tootal Broadhurst Lee Oompagiy Limited.

Hereby enters disclaimer to claims 1, 2, 3, 4, 5, and 7 in said specification.

[Ofiicz'al Gazette December 24, 1.946.] 

